@jkandasa Brilliant - thank you!!!

I don't know why but now OTA works better; I still get quite some NACKs on the gateway but at least most of the times the OTA is successful even with signing enabled. With ACK enabled the transfer speed is at least 4/5 times slower

@jkandasa Great! Thanks for pointing me out. I'll take a look. Regards

Testing now and so far the mysensors smartsleep etc is working perfectly. What a great controller, thank you for your hard work. I will maybe switch to this in place of Demotic.

Ok, I feel pretty dumb not to have thought of it before, but I've found the issue. For the sake of anyone running in the same issue, if you are running an ad blocker, try to disable it first. Looking at the request in Chromium, it said "ERR_BLOCKED_BY_CLIENT" Turning off the ad blocker resulted in a dashboard as you would expect it. Sorry for bothering you for something I should have thought of, and thank you for your support.